A pin mat is a sheet-like article comprised of a backing and a multiplicity of resilient pins or fingers projecting from one face of the backing to provide a supporting bed for medical instruments, the instruments being held in place on the mat by the resilient pins or fingers. The mat is often associated with a sterilization tray having perforate walls to facilitate sterilizing instruments supported on the mat within the tray. During the sterilization process, a cover is placed over the open top of the tray and the tray is placed in an autoclave. High pressure steam injected into the autoclave enters the tray through the holes in the tray walls and comes into sterilizing contact with the instruments supported on the mat. Usually, the tray is provided with an antimicrobial filter which permits steam to enter and leave the tray but which excludes bacteria so that when the tray is removed from the autoclave, the tray contents remain in a sterilized condition.
When pin mats were originally placed in sterilization trays, it was found that the mat backing covered the vent holes in the bottom wall of the tray so that steam could only enter the tray through the holes in the tray side walls and cover. This tended to prolong the sterilization time. To avoid this problem, some mats were provided with holes in the mat backing and standoffs at the underside of the mat between the holes; see U.S. Pat. Nos. 5,098,676 and 5,766,561. With such constructions, the mat backing is spaced from the bottom wall of the sterilization tray so that steam is free to flow through the holes in the tray bottom wall and pass under the mat and through the holes in the mat into intimate contact with the instruments supported on the mat. The holes in the mat also allow for some drainage of condensed moisture from the mat.
While those prior mat constructions have reduced accumulated moisture on and under the mat and enabled somewhat shorter sterilization times, they still have certain disadvantages. More particularly, the prior mats have backings which are flat and the holes therein are relatively small so that fluids do not tend to flow along the surface of the mat. Therefore, during the sterilization process, condensed moisture can still form and collect on the upper surface of the backing between the holes therein. These small moisture pools provide sites for bacterial growth within the tray.
Another problem with conventional mats is due to the fact that their resilient pins or fingers are packed too densely. Resultantly, the instruments on the mat tend to rest on the tips of the pins rather than against the sides of the pins which would allow the pins to minimize lateral movements of the instruments on the mat. It follows also that if the pin count of the prior mats is excessive and the backing holes are smaller, the amount of material required to make those mats is also excessive.